A street light is mounted at the top of a 20- ft tall pall. A man 6 ft tall walks away from the pole with a speed of 5 ft/sec along a straight path.

A street light is mounted at the top of a 20- ft tall pall. A man 6 ft tall walks away from the pole with a speed of 5 ft/sec along a straight path. How fast is the tip of his shadow moving when he is 40 ft away from the pole?